1. Field of the Invention
The present invention relates to an intake control device for an internal combustion engine.
2. Description of Related Art
Conventionally, intake control devices for an internal combustion engine have been known to generate a whirl flow in an axial direction (tumble flow) in a combustion chamber of the internal combustion engine by reducing a cross-sectional area of an intake passage to the internal combustion engine. As a result, an efficiency of combustion in the combustion chamber is enhanced for improving a fuel efficiency (fuel economy). Also, an engine performance such as an engine output and an exhaust gas emission, is improved.
The tumble control valve (valve unit), which generates a tumble flow in the combustion chamber of the internal combustion engine, includes a housing 106 and a valve 107 as shown in FIGS. 3A, 3B, and 4. The housing 106 is received in an intake manifold 103, which is connected with an intake manifold attachment surface 102 of a cylinder head 101 of the internal combustion engine. Specifically, the housing 106 is received in a housing receiving chamber 104 of the intake manifold 103. Also, the valve 107 is received in the housing 106 for opening and closing a passage.
There is provided a first gasket 111 between the intake manifold attachment surface 102 of the cylinder head 101 and the intake manifold 103 in order to prevent intake air from leaking to exterior. Also, there is provided a second gasket 112 between a receiving chamber wall surface 105 (internal wall surface) of the intake manifold 103 and the housing 106 in order to elastically support the valve unit in the housing receiving chamber 104.
The housing 106 is provided with two valve bearing portions 113, each of which defines a bearing fitting hole (bearing hole) therein. Two bearings 114 are fitted with hole wall surfaces of the bearing holes in a fixed relation. Also, circular slide holes 115 are defined inside the two bearings 114 for pivotally support both axial end portions (two valve slide portions) of the valve 107 along a rotational axis such that the valve 107 is slidable in a rotating direction.
The valve 107 of the valve unit includes a rotational shaft 116 that is rotatably received in the housing 106 (bearing hole). Also, the valve 107 includes an opening 117 (notch) at a top end portion of the valve 107 along a vertical axis or in a gravitational force direction for generating the tumble flow in a fully-closed state of the valve 107, where the valve 107 is fully closed as shown in FIG. 4.
The first gasket 111 functions to seal or tightly seal an annular clearance defined between the intake manifold attachment surface 102 of the cylinder head 101 and a bonding surface of the intake manifold 103. Also, the second gasket 112 functions to seal or tightly seal another annular clearance defined between an internal wall surface 105 of the intake manifold 103 and the housing 106.
The intake control device for the internal combustion engine, as shown in FIGS. 3A, 3B uses the second gasket 112 to elastically support the valve unit in the housing receiving chamber 104 of the intake manifold 103. In the above, the second gasket 112 is provided between the internal wall surface 105 of the intake manifold 103 and the housing 106 in a direction perpendicular to the intake air flow direction.
In contrast, a necessary clearance that is required to smoothly rotate the valve 107 is defined between (a) a slide surface of each of both axial end portions of the valve 107 along the rotational axis and (b) a hole wall surface of each of the slide holes 115 of the two bearings 114.
Also, the housing 106 includes an annular end surface 121 on a downstream side of the housing 106 in the intake air flow direction, and the annular end surface 121 faces with the intake manifold attachment surface 102 of the cylinder head 101 and is spaced from the intake manifold attachment surface 102 by a predetermined clearance (clearance in the intake air flow direction).
FIGS. 3A, 3B, and 4 show the intake control device for the internal combustion engine, in which there is defined a clearance between the rotational shaft 116 of the valve 107 and each of two bearings 114 in order to avoid limiting a smooth rotation of the valve 107. In the intake control device for the internal combustion engine, when the valve 107 is fully closed or is at a fully closed position, the valve 107 severely receives vacuum pressure of intake air in the internal combustion engine, and thereby the valve 107 may be displaced toward the downstream side in the intake air flow direction by an amount equivalent to the clearance.
Specifically, if the valve unit is displaced toward the downstream side in the intake air flow direction when the valve 107 is fully closed, the annular end surface 121 of the housing 106 severely collides with the intake manifold attachment surface 102 of the cylinder head 101 and thereby causing a large collision noise (hitting noise). As a result, the noise may provide an unpleasant abnormal noise to a driver.
In order to deal with the above, there is known an intake control device for the internal combustion engine, in which an upstream side end surface of the housing is pressed by an elastic member, and in which a downstream side end surface of the housing is pressed by a projection portion that projects from a receiving chamber wall surface of the intake manifold toward the intake passage. Thus, the unwanted movement of the valve unit in the receiving chamber of the intake manifold or the displacement of the valve unit in the intake air flow direction is limited (for example, JP-A-2007-046470 corresponding to US20070028891).
However, in the above conventional intake control device for the internal combustion engine described in JP-A-2007-046470, the elastic member for pressing the upstream side end surface of the housing is separately provided as a separate component in addition to first and second gaskets 11, 112. As a result, the number of components and assembly manpower is increased, and thereby causing an increase in cost disadvantageously.